The present invention relates to a stabilizing power-supply circuit.
As shown in the block diagram of FIG. 1, in the conventional stabilizing power-supply circuit, it has been proposed one portion of the output of the oscillation circuit to be caused a negative feedback to a control circuit composed of a control transistor through a comparison circuit to control the oscillation circuit so that the stabilized output may be provided. However, in such a stabilizing power-supply circuit, the efficiency was reduced due to the inevitable loss, such as the collector loss of a control transistor, caused in the control circuit. Moreover, in the high power, a radiation unit had to be made large due to more heat generated by the control transistor, thus interfering with the smaller size and lower cost of the power-supply apparatus. To settle such problems as described hereinabove, the oscillation transistor of the oscillation circuit is expected to be directly controlled by the negative feedback signal after the elimination of the control circuit. However, the direct controlling of the oscillation transistor after the elimination of the control circuit causes the high output voltage during the no-load, thus causing new problems such as the apparatus damages, troubles or the like.